Railway wheels are known in different versions, for example with a wheel flange that rolls along the rail and is shrink-fitted onto a wheel body or with a wheel disc comprising solid material in which the running surface is configured as an integral part of this wheel disc. Irrespective of the specific version, railway wheels are components in the wheel/rail system which are exposed to high loadings and are subject to unavoidable wear as a result of their contact with the rail. The raceways undergo wear as a result of their contact with the rail head and the wheel track flanges undergo wear as a result of their contact with the inside surface of the rail head, especially on curved tracks and when passing through switches. In addition to this functionally related wear on the wheels, it is also possible for material defects to occur as a result of overloading the wheels or production errors during manufacture. As a result, railway wheels are regularly investigated for material defects either manually or semi-automatically with established methods (ultrasound, eddy currents, X-ray), so as to guarantee continued safe vehicle operation. A train incorporates a large number of wheelsets, however, meaning that inspections of this type entail lengthy downtimes and require highly qualified personnel, as well as calling for the extensive use of test technology. Various state-of-the-art test methods have already been disclosed in this regard.
For example, DE 693 03 989 T2 describes a technical solution that is, in a preferred embodiment, suitable for use by manufacturers of railway wheels in testing the hardness and residual stresses in railway wheels: The hardness test is carried out by ball indentation and the residual stress test by ultrasound, in which case a scaffold-like device is used which features numerous holding and displacement devices for handling the measuring technology.
DE 103 52 166 B3 concerns a device designed for use in the workshop for semiautomatically measuring the surface composition of the running surface of railway wheels in installed condition. In this case, a measuring device for each of the two wheels of a wheelset is arranged on a measuring platform. Once both wheels have been raised somewhat and set in rotation, the running surface of each wheel is scanned step-by-step by a measuring beam. The distances measured by the measuring beam between the measuring device and the running surface of the wheel are evaluated by computer technology in order to estimate out-of-roundness values and surface composition.
DE 11 2006 002 123 T5 discloses a device with a so-called gauge head that can be mounted on a railway wheel in a releasable connection and has several sensors assigned to it for measuring typical geometrical components of the railway wheel, for example a wheel flange height sensor and a wheel flange thickness sensor. This gauge head is in an active connection with a control and evaluation device.
DE 199 24 781 A1 describes a further technical solution for checking a railway wheel installed in a rail vehicle. In this case, a railway train is driven over a section of test track at low speed. A test probe is propelled by a linear drive on a guide rail parallel to the test track and is initially set to the travelling speed of the train, after which the test probe contacts the railway wheel.
A solution involving a similar approach is disclosed in DE 199 43 744 B4, in which case the wheel flange and the clamping edge are, in a preferred embodiment, tested simultaneously by means of several probes while the train is moving into a maintenance hall along a test track for routine inspections.
Although a large number of technical solutions have been disclosed for inspecting railway wheels, further development is nevertheless still required. This is due in particular to an ever-increasing demand for automated, robust and efficient test technology.
The task of the present invention is to create a technical solution by means of which various configurations of railway wheels and their components or component sections that are exposed to wear can be tested in a short time and at an acceptable cost in order to identify possible damage. In particular, the railway wheels should be inspected in override mode so that the test results for a complete train can be prepared during the passage time over an allocated test device. In addition, detection of various types of defect should be guaranteed during the test process,
In terms of the procedure, this task is accomplished in that the rolling railway wheelset passes through a spatially restricted magnetic field that is coupled through the rails along which the allocated rail vehicle is guided. For this purpose, a device is used in which there is an electromagnet arranged between the rails, and on which a measuring coil is also configured for registering changes in the magnetic flux. Advantageous embodiments are dealt with in subordinate claims, the technical characteristics of which are explained in more detail in the design example.
In accordance with the present invention, the material test of railway wheels is carried out by analysing the magnetic flux that passes through a loaded, rolling wheelset. For this purpose, a track segment is prepared in such a way that a left and a right rail form the pole shoes of a magnet in terms of function. Railways wheels of the normal version consist of several components made of ferromagnetic steel, especially a wheelset shaft, two wheel discs as well as possibly also brake discs and/or drive gears. The magnetic flux through the wheel from one rail of the track to the other is modulated by the Hertzian contact surfaces of the wheel/rail, by the seats of the wheel discs on the shaft and by the so-called Barkhausen noise in the pre-magnetised and rotating material exposed to alternating loads. The modulations in a precisely rotationally symmetrical wheel body are different from those in a wheel body that has singularities in its structure or in the running surfaces. As a result, the signals differ depending on the current wheel condition. The corresponding signal profiles are analysed, classified and allocated to specific wheelset conditions according to their characteristics.
As a result, the present invention provides a technical solution for verifying material defects in installed railway wheels while a train is travelling, in which case the underlying approach to the solution involves troubleshooting in the rolling wheelset using magnetic flux changes.